1. Field of the Invention
The present invention relates to an image processing apparatus, control method, and storage medium.
2. Description of the Related Art
Reduction of the power consumption and voltages of recent electronic devices promotes reducing power supply voltages supplied to rewritable devices typified by an FPGA. Also, multiple supply voltages are used because not only one but a plurality of voltage levels are available for a rewritable device along with the advance of multifunctional circuit operations for the rewritable device. Accordingly, the allowable fluctuation width of a supply voltage to a rewritable device becomes narrow, and stable quality is requested of a power supply voltage to be supplied.
The user can write circuit information in a rewritable device by a configuration operation. User-defined circuit information can be programmed in the rewritable device, implementing a circuit operation the user wants. After the rewritable device is powered, user-defined circuit information stored in advance in a memory typified by a ROM is written in the device by the configuration operation. However, when the power supply to the rewritable device is shut down and turned on again, the rewritable device returns to the initial state, so user-defined circuit information needs to be written again in the device by the configuration operation.
The configuration operation often requires a memory such as a ROM other than the rewritable device in order to transfer data of stored user-defined circuit information to the rewritable device. The rewritable device can define a supply power area for each circuit block in the device, and control the power supply for each area. In this case, circuit data is generated by designating mapping of circuit blocks to be written in the device to the same power supply area. The circuit data is stored in advance in a memory such as a ROM, and a circuit block can be generated for each specific power supply by the configuration operation.
In some cases, the rewritable device has function cells corresponding to a plurality of modes, and the voltage level is lower than that of a normal cell. The rewritable device generally operates at a voltage level lower than the driving voltage of an operation cell. In this case, the operation speed becomes lower than that of a normal operation cell. When, therefore, a low-power consumption cell is used, the operating frequency of a written user circuit becomes lower than that of a normal operation cell. However, if the user operates the rewritable device in consideration of the voltage level, the rewritable device operates without any trouble even using a low-power consumption cell as long as a circuit having an operating frequency corresponding to the voltage level is set. A low-power consumption cell and normal operation cell can be combined to create circuit data the user wants. In this case, user circuit data is generated by configuring a specific circuit using a low-power consumption cell and another specific circuit using a normal operation cell.
The power supply may unstably supply power to the rewritable device, or fall outside the allowable voltage range of the rewritable device. For example, the power supply state at a location where a rewritable device-embedded system is installed may be unstable, or the power supply on a rewritable device-embedded substrate may be unstable.
A rewritable device typified by an FPGA may malfunction if the supply voltage falls outside the device use range. If the supply power is lower than a specified one, the internal circuit of the rewritable device may be initialized. When the supply voltage to the rewritable device falls outside a specified level in a rewritable device-embedded system, processing in the rewritable device is sometimes locked and fails to output desired data. In this case, a destination circuit connected to the rewritable device falls into a special state. In this state, the whole system further malfunctions, and hangs up depending on the circumstances.
Upon generation of the hang-up, the system needs to be reset or powered again to return it. However, if the power supply voltage is in the same state as that before the return, the rewritable device becomes unstable again.